Simona Halep was clinical in her disposal of Naomi Osaka. Picture: Getty Images

There had been little sleep in the lead-up to the match as she battled "pain everywhere" in the wake of her 4-6 6-4 15-13 win over American Lauren Davis on Saturday, but now that she can win with the injury in tow, she is confident.

"Improving? I'm not sure because I'm running a lot," she said.

"Maybe I get used to the pain and I'm not thinking that much that something can happen. Just taking every point.

"I'm trying to play 100 per cent, which I was close to yesterday, to run normal and to run a lot.

"But I still feel it. It's there, but I can handle it."

Making the last eight is a scenario that she admitted she never could have imagined having entered the tournament under the injury cloud and re-aggravating her ankle complaint in her first round clash with Australian teenager Destanee Aiava.

"I didn't expect to do quarterfinals," Halep said.

"I didn't expect also to stop the tournament, even if I was injured. I had nothing clear in my head.

"I just went on court, (to) take it match by match.

"The match against Davis was huge for me, maybe gave me a little bit more confidence that my body is OK and I can resist the tough matches. Now I'm more confident."

She will have an MRI on the troublesome ankle after the tournament, and said that there is no break but that "ligaments are very stretched".

Osaka threw everything at the top ranked Halep, but the Romanian cast aside her ankle concerns to break the youngster twice in the first set and steamroll the second set to ensure the match was over in half the time she took to dispose of Davis.

Japan’s Naomi Osaka lost no fans in her inspiring Aus Open run. Picture: AFP

She "dominated", she said, executing her plan to perfection.

"I knew that every ball is important. If I take the lead in the second set more, then I'm going to break her a little bit physically and also mentally. So I did it well," she said.

"I moved her. I stayed there. I tried just not to miss that much. I tried also to push her back, which I did. She couldn't dominate the game. I did, I dominated. I went to the net a lot. I finished the point when I felt that it's time."

Halep has spent almost nine hours on court this tournament - more than any other remaining woman in the draw.